Nagios Server Load Baseline



I have been using Nagios effectively in our monitoring scheme for a couple of years. We have grown, and we are now watching approx 550 hosts using approx. 750 active checks. Management has asked the question when is the monitoring server too busy? I would also like to know that. I am seeing warnings lately that the server is seeing more than 250 processes RSZDNT. Is this just a low threshold or should I start to worry? Is there a page or document somewhere that calls pout the baseline specs for a healthy Nagios server? Of course it depends on CPU and memory and network etc, but I am hoping there are some kind of general stats avaiilable.

Thanks in Advance